Various organic antimicrobial agents, such as quaternary ammonium salts, phosphonium salts, and N-halamine compounds, have been extensively investigated over the past 20 years. Compared with halogens, which are inorganic, N-halamines are more stable and less corrosive, and their numerous sought-after qualities (i.e., effectiveness at killing toward a broad spectrum of microorganisms, long-term stability, the possibility of recycling, low cost, and safety for humans and the environment) make N-halamines particularly attractive. The dissociation constant of N-halamine compounds in water is relatively low and varies based on chemical structure in the order amine<amide<imide. However, in the presence of microorganisms, oxidative halogen e.g., Cl transfer from the N-halamine bond to the microorganism is significantly favored over hydrolysis. Amine-halamine is the most stable of all halamine bonds but has a slower bactericidal rate than amide-halamine. In contrast, imide-halamine has a rapid bactericidal rate because it is the least stable of all halamine bonds and can rapidly release active Cl into the medium.
Compounds containing amide-halamine bonds are considered the most practical for industrial applications because they exhibit a moderate rate of transfer of the oxidative Cl from the N-halamine to bacteria in aqueous solution and thus provide reasonably rapid bactericidal activity. Although the hydrolysis constant of amidehal amines is in the range of 10−8, the Cl transfer to the bacteria is the more favorable process.
Bacterial attachment to surfaces leading to the formation of communities of bacterial cells is a major problem in many diverse settings. This sessile community of microorganisms, also termed a biofilm, is attached to an interface, or to each other, and embedded in an exopolymeric matrix. It manifests an altered mode of growth and transcribes genes that free-living microorganisms do not transcribe. The most characteristic phenotype of the biofilm mode of growth is its inherent resistance to disinfection, antimicrobial treatment and immune response killing.
The inherent resistance of biofilms to killing and their pervasive involvement in product contamination, pipe clogging and implant-related infections has prompted for various industrial applications such as drinking water distribution systems and food packaging.
U.S. Pat. No. 8,211,361 discloses one or more acyclic-amine structures being halogenated to form one or more acyclic N-halamine structure, and uses same for functionalizing a surface of an object to control microbial contamination of a surface.
CN Patent No. 103,044,611 discloses polymeric antibacterial nano-particles and magnetic antibacterial nano-particles containing halamine functional groups.